Recently, the strength and frequencies of earth quakes have increased globally, and due to this, an earthquake-resistant design of important facilities, such as a bridge, a building, and a nuclear power plant has become increasingly important. In particular, when a large displacement is generated in a pipe that is directly concerned with the safety of a nuclear power plant, a great problem may be caused in the nuclear power plant. The need for a pipe support technique is increasing in order to prevent losses caused by pipe damage.
In a vibration-proofing system for supporting a pipe in a nuclear power plant as described above, a buffering mechanism is needed in order to stably support the pipe on a support structure, and to buffer and absorb a shock force, such as an earthquake, thereby preventing the pipe from being damaged.
In general, a hydraulic-buffering mechanism, which has been used in a bridge in order to buffer and absorb a shock force that abruptly acts between two structures by an earthquakes or the like while receiving a normal load that gradually acts between the two structures, is composed of: a cylinder that is filled with a hydraulic fluid; a piston that is movably installed within the cylinder and is formed with orifices; and a rod that is connected to the piston.
Such a conventional hydraulic-buffering mechanism is difficult to manufacture, maintain, and repair because it is necessary to maintain fluid-tightness in the cylinder. Accordingly, it costs a lot to manufacture the conventional hydraulic-buffering mechanism, and the conventional hydraulic-buffering mechanism is not suitable for use in a nuclear power plant that requires stable performance maintenance for a long period of time.
Further, because the viscosity of the hydraulic fluid is strongly influenced by a temperature change, the conventional hydraulic-buffering mechanism has a disadvantage in that it suffers from a serious performance deviation depending on a temperature.
In addition, the conventional hydraulic-buffering mechanism has a problem in that its shock absorption is unsatisfactory.
Further, the conventional hydraulic-buffering mechanism also has a problem in that it is difficult to adjust the damping performance thereof.
Due to the above-mentioned disadvantages, the conventional hydraulic-buffering mechanism is not suitable as a device for supporting a pipe of a nuclear power plant or the like.
Korean Patent No. 10-1200692 (entitled “Friction Damper” and invented by CHO, Young Cheol and LEE, Yu In (hereinafter, referred to as “Patent Document 1”) and Korean Patent No. 10-1512122 (entitled “Pendulum-type Friction Damper and invented by CHO, Young Cheol and CHO, Sung Kook (hereinafter, referred to as “Patent Document 2”) disclose inventions developed to solve the problems of the hydraulic-buffering mechanism. The disclosures of Patent Documents 1 and 2 are incorporated herein in their entireties by reference.